U.S. Pat. No. 3,384,856 entitled "Multiphase Electric Power Distribution System" describes the close attachment of high ampere-rated bus bar conductors by means of insulated bolts and insulative coatings. The close coupling of the bus bars was intended to provide good heat transfer away from the bus bars to the heat-sinking metal support frame. The absence of thermally stable and moisture resistant insulative material prevented the close coupling concept from commercial feasibility until the development of epoxy electrical insulating material. U.S. Pat. No. 4,804,804 entitled "Thermally Efficient Power Busway Housing" describes electric bus bar conductors employing epoxy material as in insulation coating that are bolted together by means of insulated bolts.
The thermal and electrical insulating properties of the epoxy material render the epoxy superior to other plastic resins for bus bar insulation coatings. The tendency of the epoxy to react with moisture is controlled by the addition of proprietary hydrolytic materials to the epoxy composition. However, to insure good long term resistance to extreme moisture conditions, the bus bar manufacture subjects sample epoxy-coated bus bars to extreme water submersion and electrical energizing testing before qualifying the epoxy material for large scale production quantities.
Current practice is to subject representative numbers of sample epoxy-coated bus bars to such "water-test" conditions for at least one thousand hours before qualifying the epoxy material for large scale bus bar insulation. The long tests and evaluation processes involved add to the overall cost of the already expensive epoxy material. It would be economically advantageous to provide a simple short time test for qualifying epoxy material for bus bar insulation coatings.
One purpose of the invention is to describe a simple apparatus and process for qualifying epoxy as an electrical bus bar insulation material in a substantially shortened time frame.